Economic strength poses a possible risk that the Fed might find it necessary to increase interest rates even beyond May. With that comes the risk that the economy could be slowed substantially, which is something that had been taken off the table at least in the last month.

What the Fed is telling us here is that they are not of the mind to put so much tightness on the economy as to jeopardize modest growth in the year ahead, and the market is taking great delight in that.